The present invention relates to preparation of sheeted plastic articles having undulated, or waved, marginal portions.
Products formed from plastic and plasticizable materials, i.e., pliable and malleable materials which may be shaped and formed, to have undulated or waved marginal portions (hereinafter solely referred to as "waves" and "waved portions") are known to have been produced by extrusion techniques. Such products include food products such as sheets of farinaceous materials, including, illustratively, dough sheets employed for lasagna products. When employing extrusion techniques, the waves are created by an elongated slit die, i.e., extruder exit orifice, which has a narrower opening at its sides than in a central portion between two side marginal portions. Thus, the marginal portions of the extrudate flow from the die at a rate different from the flow rate of the central portion, thereby forming the two marginal portions in a wave form.
Additionally, U.S. Pat. No. 4,289,470 discloses a further means for preparing dough strips having waved marginal portions wherein the apparatus has a pair of rolls having marginal fluted portions which are positioned to mesh and crimp the marginal portions of a sheet of material passed between the rolls.